Plastic molding strips are provided for various goods such as appliances and motor vehicles in order to interconnect other parts and to minimize damage to the article to which it is connected through inadvertent, slight contact. In order to enhance the appearance of such molding strips, such molding strips have included a decorative plastic strip such as a Mylar polyester film having a vacuum metallized layer formed thereon. In order to protect the polyester film yet still allow the polyester film to be seen with its metallized layer, the polyester film is often times covered by a clear plastic layer, such as clear polyvinyl chloride (i.e. PVC).
Frequently, the clear PVC totally encapsulates the molding strip in order to prevent separation between the underlying plastic body and the clear PVC. However, total encapsulation by the clear PVC is undesirable for a number of reasons including inefficient use of the clear PVC.
One proposed alternative to total encapsulation by the clear PVC of the molding strip is to use multiple dies, the last one of which applies a top coat of clear PVC to the extruded plastic body after the decorative plastic strip has been placed on the plastic body.
Another reason to use multiple dies is that the decorative plastic strip would commonly break under the high temperature and pressure conditions existing in the die forming the plastic body.
One disadvantage of this method is that the clear plastic layer has a tendency to separate from its underlying plastic body during use of the molding strip, especially when the molding strip encounters impact at extreme temperatures or when the molding strip is used around corners having a relatively small radius. Also, the decorative plastic strip has a tendency to wrinkle or buckle during use of the molding strip to thereby detract from the appearance of the molding strip. Consequently, many manufacturers have decided to provide molding strips without such a decorative plastic strip.
The Angioletti et al U.S. Pat. No. 4,087,223, Gans et al U.S. Pat. No. 4,269,897, Azzola U.S. Pat. No. 4,381,273, Preis U.S. Pat. No. 4,470,943, Zoller U.S. Pat. No. 4,563,141, Adell U.S. Pat. No. 4,581,807 and Paul U.S. Pat. No. 4,643,659 all deal with extrusion of more than one type of plastic to form a resulting plastic part. For example, the U.S. Patent to Azzola discloses a sealing strip, including a channel-shaped attachment profile of rubber in which a metallic reenforcing strip is embedded. The profile has an external coating layer of sponge rubber with an outer surface rendered velvety by abrasion.
The U.S. Patent to Gans et al discloses a process for extruding resilient, impact-resistant, thermoplastic strips having a metallic appearance by providing a non-metallic film strip of material and having a vapor-deposited, metallized surface. The film strip has melting and deformation temperatures higher than those of the transparent thermoplastic extruded thereon and resiliency and an elasticity at least as high as the resiliency and elasticity of the transparent thermoplastic when extruded thereon. While feeding the film strip through a crosshead die, the thermoplastic material is extruded about the metallized film strip and the resilient impact-resistant thermoplastic strip has a metallic appearance produced thereby.